1. Field Of The Invention
The field of art to which this invention pertains includes power transmission mechanisms, such as change speed transmission gearing and more specifically transmissions having multiple input and output gears that are particularly adapted for highway type vehicles, such as truck tractors.
2. Description Of The Prior Art
In this time period of decreasing energy supplies and increasing fuel costs, it becomes imperative to increase the efficiency of all vehicles, especially that of commercial and industrial vehicles, such as trucks. One way of accomplishing this goal is to reemphasize the importance of change speed transmissions having multiple input and output geas so as to provide a large number of gear ratios to permit full utilization of the most favorable torque ratio band of the prime mover.
In addition, such transmissions should utilize a minimum number of components, such as gears, shafts and clutches, so as to not only minimize the complexities thereof but also to maximize the reliability thereof. The reduction of the numbers of transmission components also saves considerable weight and space, both of which are important from the energy consumption and efficiency standpoint.
Furthermore, transmissions of this type should be constructed so as to have a minimum number of shafts so as to reduce the number of transmission through-bores to a minimum and additionally, to minimize transmission housing machining costs.
There are prior art transmissions with triple inputs, such as those shown in U.S. Pat. No. 2,316,503 (issued Apr. 13, 1943) to Curtis, however, this transmission utilizes dual countershafts and is markedly more complex in its construction.